Quote:
Originally Posted by Vettezuki
Uhh, 5250 is used in the equation, not because of the math equation. And to be extra annoying, it's actually 5252, derived thusly.
The constant 5252 comes from (33,000 ft·lbf/min)/(2π rad./rev.).
NOTE: The 33,000 ft.lbf/min. is the definition of one HP. Why it's divided by 2π rad./rev. I don't recall. But that's the constant you use.
HP = T[ft.lbf.] x RPM/5252
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I did mention about the 5252 a couple pages ago. The average horse could lift a 550 pound weight one foot in one second, thereby performing work at the rate of 550 foot pounds per second, or 33,000 foot pounds per minute, for an eight hour shift. That is where the 33,000 ft. lb per minute came from. 550*60= 33,000.
(2π rad./rev.). converts radians to revolutions. There are 2 pi (3.14) or 6.28 radians to 1 rev.